480 THE DIGESTION OF CELLULOSE. [BOOK II. 



of the saliva and, under the influence of its diastatic ferment, the 

 conversion of starch into dextrins and sugars proceeds. At the same 

 time much of the soluble matter of the food (salts, sugars, gums, &c.) 

 must be extracted and pass into solution. 



Though the rumen produces no enzyme, and merely affords a 

 suitable cavity in which the diastatic enzyme of the saliva may 

 exert its action, it seems invariably to be the habitation of innumer- 

 able micro-organisms which provoke in its contents fermentations 

 accompanied by the evolution of gases and by the development of 

 fatty acids. In the rumen, a decomposition of cellulose due to the 

 action of micro-organisms doubtless occurs. 



The reticulum, it may be assumed, exerts no chemical action on 

 the constituents of food, its function being, as we have stated, that of 

 a distributor of matter. Nothing is known definitely as to the 

 function of the psalterium. Tiedemann and Gmelin found its juice 

 acid and discovered in it acetic acid, doubtless the product of fermen- 

 tation. The function of the fourth, or true, stomach is exactly similar 

 to that of the stomach of man or the carnivora. It would appear, 

 however, from the observations of Bidder and Schmidt, that the pro- 

 teolytic activity of the gastric juice which it forms is relatively feeble. 



on tne di- Although the excrements of the herbivora contain 

 gestion of eel- } ar g e quantities of cellulose, the attention of physio- 

 Srbivora logical chemists has long been directed to the question 



whether any part of the cellulose introduced into the 

 alimentary canal undergoes decomposition and, if so, whether the 

 products are of such a nature as to be of some importance in nutri- 

 tion. No enzyme is found in the alimentary canal nor is any un- 

 organised ferment known which possesses the power of digesting 

 cellulose. We are, however, in possession of facts which leave no 

 room for doubt that cellulose can be decomposed through the agency 

 of micro-organisms, and that this process occurs in the alimentary 

 canal of the herbivora. 



Tappeiner 1 found that cotton-wool when added to a solution of 

 extract of meat mixed with bacteria obtained from the rumen under- 

 went a process of fermentation accompanied by the evolution of 

 gases and disappeared, fatty acids being found in the solution, 

 v. Kniriem 2 shewed that during the process of digestion in herbivora 

 an appreciable quantity of cellulose disappears, and even found that 

 the cellulose of paper disappeared in its passage through the alimen- 

 tary canal. Victor Hofmeister 3 , by digesting hay made from young 

 grasses with the liquid found in the intestines of slaughtered horses, 



1 Tappeiner, ' Untersuchungen iiber die Gakrung der Cellulose, insbesondere iiber 

 deren Losung im Darmkanale,' Zeitsch. f. Biol. Vol. xx. (1884), p. 52, and Vol. xxn. 

 1886, p. 105. 



2 von Kniriem, ' Ueber die Verwerthung der Cellulose im thierischen Organismus,' 

 Zeitsch. f. Biol, Vol. xxi. (1885), pp. 67139. 



3 V. Hofmeister, ' Ueber Cellulose- Verdauung beim Pferde,' Archiv /. wissensch. u. 

 prakt. Thierheilkunde, Vol. xi. (1885), Heft 1 and 2, quoted by Neumeister, Phys. 

 Chem., p. 235. 



